JAK belongs to the family of tyrosine kinases involved in inflammation, autoimmune diseases, proliferative diseases, transplant rejection, impaired cartilage turnover-related diseases, congenital cartilage malformations, and/or diseases associated with excessive secretion of IL6. The present invention also provides a method for preparing the compound or a pharmaceutical composition comprising the compound, and a method for preventing and/or treating inflammation, autoimmune diseases, proliferative diseases, transplant rejection, impaired cartilage turnover-related diseases, congenital cartilage malformations, and/or diseases associated with excessive secretion of IL6 by administrating the compound of the present invention.
Janus kinase (JAK) is a cytoplasmic tyrosine kinase that transduces a cytokine signal from a membrane receptor to an STAT transcription factor. The prior art has described four members of the JAK family: JAK1, JAK2, JAK3 and TYK2. When cytokines bind to their receptors, JAK family members are auto-phosphorylated and/or trans-phosphorylated from each other, followed by STATs phosphorylation, and then are migrated into the cell nucleus to regulate the transcription. JAK-STAT intracellular signal transduction is suitable for interferons, most interleukins, as well as various cytokines and endocrine factors, such as EPO, TPO, GH, OSM, LIF, CNTF, GM-CSF and PRL (Vainchenker W. et al. (2008)).
A combinatorial study of a genetic model and a small molecule JAK inhibitor has revealed the therapeutic potential of several JAKs. It has been confirmed by mouse and human genetics that JAK3 is an immunosuppressive target (O'Shea J. et al. (2004)). A JAK3 inhibitor has been successfully used in clinical development. At first, it was used in organ transplant rejection, and later also used in other immunoinflammatory indications such as rheumatoid arthritis (RA), psoriasis and Crohn's disease (http://clinicaltrials.gov/). It has been confirmed by human genetics and mouse knockout studies that TYK2 is a potential target for immunoinflammatory diseases (Levy D. and Loomis C. (2007)). JAK1 is a new target in the field of immunoinflammatory diseases. The heterodimerization of JAK1 and other JAKs arouses a transduction of cytokine-driven pro-inflammatory signaling. Thus, it is expected that inhibition of JAK1 and/or other JAKs has a therapeutic benefit for a series of inflammatory diseases and other diseases driven by JAK-mediated signal transduction.